Incorrect Payload Parsing in 64-Byte CAN FD Frames from BLF Files Using python-can

[ppd2mmb]

Describe the bug

I encountered an issue when using python-can to parse BLF files. Specifically, when parsing BLF files generated by certain tools(Tsmaster), I observed incorrect payload data in 64-byte CAN FD frames. The problem consistently appears starting at 48 bytes. However, the same BLF files can be parsed correctly using Tsmasterand CANoe.
CANoe:

python-can:

Please investigate this issue. Thank you!

To Reproduce

I have attached the BLF file.
2024_12_31_14_09_35.zip

from can import BLFReader
import sys
def read_blf(file_path):
    try:    
        with BLFReader(file_path) as reader:
            for msg in reader:      
                if msg.arbitration_id== 0x6a9:
                    print("***********************************")
                    print(f"Raw Data: {msg.data.hex()}")             
                    print(f"Timestamp: {msg.timestamp} s")
                    print(f"Channel: {msg.channel}")
                    print(f"ID: {hex(msg.arbitration_id)}")
                    print(f"Data: {msg.data.hex()}")
                    print(f"Length: {msg.dlc}")
                    print("-" * 50)
                    print("***********************************")
    except Exception as e:
        print(f"read BLF file error: {e}")

if __name__ == "__main__":
    if len(sys.argv) != 2:
        sys.exit(1)
    blf_file = sys.argv[1]
    read_blf(blf_file)

Expected behavior

Additional context

OS and version: windows 11
Python version:Python 3.11.9 (tags/v3.11.9:de54cf5, Apr 2 2024, 10:12:12) [MSC v.1938 64 bit (AMD64)] on win32
python-can version:4.5.0
python-can interface/s (if applicable):

[zariiii9003]

Thank you for the code snippet and example file 👍

I checked the first message object in your file. The mValidDataBytes field has a value of 64, but the object only contains 48 data bytes. This causes python-can to read parts of the next object.
This is a bug in TSMaster, but the python-can implementation could be more robust, too.

Edit: Like CANoe, binlog.dll also adds padding with 0x00 bytes, so maybe this is valid according to blf format...

[ppd2mmb]

Thank you for the code snippet and example file 👍

I checked the first message object in your file. The mValidDataBytes field has a value of 64, but the object only contains 48 data bytes. This causes python-can to read parts of the next object. This is a bug in TSMaster, but the python-can implementation could be more robust, too.

Edit: Like CANoe, binlog.dll also adds padding with 0x00 bytes, so maybe this is valid according to blf format...

Thank you for your response and quick fix. I have downloaded the updated script and successfully read the payload. Thanks again!